It sounds crazy, but it might just work.
The busiest train of the day is the 8:51 from Union. You could add a non-stop trip from Union to Niagara Falls departing around 9:15, and it would almost catch up to the existing trip around St. Catharines. Assuming the faster service skips St. Catharines, it can use the south track, enabling the two trains to cross the canal side-by-side if the existing train is late.
The line then narrows to a single track, so if the existing train was late, then the fast train does need to wait for it, but at least the bridge can go up and let boat traffic resume in the meantime.
Niagara Falls station has a 446-metre platform, which is just enough to fit two 8-car trains with a 9-metre gap between them.
View attachment 401936
446m platform
- 8x 26m coaches
- 1x 21m locomotive
- 8x 26m coaches (locomotive doesn't need to be on the platform)
= 9m gap
Operating on the same platform requires operating within the same signal block, and thus at an extremely slow speed. But it's not like trains fly into Niagara Falls station anyway.
Stopping a second train on the platform also requires a second raised mini-platform.
Although it may be technically be possible to run a pair of trains together to Niagara Falls, all of the above caveats, combined with the much higher operating costs compared to just cramming everyone in one 12-car train, make the above operation extremely unlikely. Better to just add an extra departure with the same stopping pattern a couple hours after the current 8:51 departure.